Vacuum printing plate mounter and registration system

Information

  • Patent Grant
  • 6397748
  • Patent Number
    6,397,748
  • Date Filed
    Monday, July 17, 2000
    23 years ago
  • Date Issued
    Tuesday, June 4, 2002
    22 years ago
Abstract
A printer plate having an integral alignment target and a printing plate mounter having a vacuum cup with an alignment member thereon to permit visual alignment of the alignment target with the vacuum cup alignment member with the vacuum cup connectable to a vacuum source so that a vacuum can draw the printing plate alignment target and the alignment member on the vacuum cup from a state of state of misalignment, if any, into precise mechanical alignment for transfer to a printing cylinder while the vacuum cup supports the printing plate.
Description




FIELD OF INVENTION




This invention relates generally to printing, and more specifically, to a vacuum printing plate mounter and registration device for mounting in register a flexographic printing plate onto a sticky back cylinder.




BACKGROUND OF THE INVENTION




One of the traditional way for mounting flexographic printing plates onto a sticky back cylinder is the use of a pair of cameras, each operatively connected to a split screen to display microdots on the printing plate. The printing plate is then manually manipulated to bring the microdots into a center screen to register the plate.




Another way for mounting flexographic printing plates onto a sticky back cylinder is by first having the plate targets aligned after which either a pneumatic punch or a precision drill is used to effect holes in the outer perimeter of the plate. The punched/drilled plates are then transferred to a pin-bar. The punched or drilled holes are then slid over pins that are affixed to the bar. The plate is then applied to its particular plate cylinder which has pre-applied sticky back material to hold the plate in place. This method take a great deal of time and money and occasionally results in the plates being deformed.




The present invention provides a vacuum printing plate mounter which uses a vacuum source to precisely align a target on printing plate with an annular member located in a vacuum cup after the vacuum cup has been visually aligned with the target on the printing plate. After mechanical alignment of the vacuum cup with the target, the vacuum cup supports and maintains the printing plate in position as the printing plate is transferred to the sticky cylinder.




DESCRIPTION OF THE PRIOR ART




U.S. Pat. No. 5,626,076 discloses a system for mounting flexible printing plates by physical register record plate and a method for physical register record plate.




SUMMARY OF THE INVENTION




Briefly, the present invention comprises a flexographic printing plate and flexographic printing plate mounter having a slide or support moveable from a down position to an up position. The slide slidably supports a vacuum cup which is connected to one end of a vacuum tube. The other end of the vacuum tube is connected to a foot operable vacuum source which is used to control the suction force of the vacuum cup to enable the vacuum cup to mechanically align with a target on a flexographic printing plate after the target and the flexographic printing plate have been visually aligned. Once the target is mechanically aligned, the vacuum cup supports the flexographic printing plate as the plate is moved from a down position to the up position where the flexographic printing plate can be the transferred to a sticky back cylinder.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

shows a perspective view of a vacuum printing plate mounter;





FIG. 2

shows a portion of a printing plate with a target and a vacuum cup;





FIG. 3

shows a side view of a vacuum cup which has a bell shape configuration;





FIG. 3



a


is a cross-sectional view taken along the lines


3




a





3




a


showing the first annular member and the second annular member inside the vacuum cup with one end of the first annular member protruding out of the vacuum cup and with both ends of the second annular body protruding out of the vacuum cup body;





FIG. 4

shows a top view of the target located on a flexographic printing plate;





FIG. 4



a


shows a cross-sectional view taken along lines


2




a





2




a


showing the depression of the channel and recess of the target on a flexographic printing plate;





FIG. 5

shows a sectional view of a close-up of how a visual alignment might appear between an annular member and a depression on the target of a flexographic printing plate;





FIG. 5



a


shows a sectional view of a close-up of mechanical alignment between an annular member and a depression on the target of a flexographic printing plate;





FIG. 6

illustrates an alignment of a target on a flexographic printing plate onto a vacuum cup by a mechanical alignment resulting from vacuum suction being applied;





FIG. 7

is a side view showing a sticky back cylinder and a vacuum printing plate mounter with flexographic printing plate arms in a down position; and





FIG. 8

is a side view showing a sticky back cylinder and a vacuum printing plate mounter with flexographic printing plate arms in an up position.











DESCRIPTION OF THE PREFERRED EMBODIMENT




Referring to

FIG. 1

, reference numeral


10


identifies a vacuum printing plate mounter of the present invention for mounting a flexographic printing plate on a sticky back cylinder.




Reference numeral


11


identifies a horizontal slide or support having a first end


11




a


and a second end


11




b


. One end of horizontal slide


11


is slidably connected to a first vertical alignment slide


47




a


and the opposite end of horizontal slide is slidably connected to a second vertical alignment slide


47




b


to allow for vertical positioning of horizontal slide


11


along arm


12


and arm


13


.




Shaft


14


rotateable supports first arm


12


and second arm


13


with shaft


14


fixedly connected to first arm


12


at end


12




b


of first arm


12


and at end


13




b


of second arm


13


to enable first arm


12


and second arm


13


to move in unison. Encircling first end


14




a


of shaft


14


is a first bearing


42




a


and a first bearing block


41




a


. Similarly, encircling second end


14




b


of shaft


14


is a second bearing


42




b


and a second bearing block


41




b


. The bearings and bearing blocks allow shaft


14


to simultaneously move or rotate support arms


12


and


13


from a horizontal position (

FIG. 7

) to the vertical position shown in FIG.


1


and FIG.


8


.




First vertical alignment slide


47




a


is carried by a first arm


12


, having a first end


12




a


and a second end


12




b


which is connected to end


14




a


of rotatable shaft


14


. Similarly second vertical slide


47




b


is carried by a second arm


13


having a first end


13




a


and a second end


13




b


which is connected to end


14




b


of rotatable shaft


14


.




The first bearing block


41




a


and second bearing block


41




b


are supported by a base plate


15


. Base plate


15


has a first end


15




a


and a second end


15




b


, a first side


15


′ and a second side


15


″ with the first bearing block


41




a


supported at first end


15




a


of base plate


15


and second bearing block


41




b


supported at second end


15




b


of base plate


15


.




Connected to end


15




a


of base plate


15


is a first transverse slide


16




a


and connected to opposite end


15




b


is a second transverse slide


16




b


. The first transverse slide


16




a


is slidable with respect to a first mounting bracket


17




a


and similarly, second transverse slide


16




b


is slidable with respect to a second mounting bracket


17




b


to permit base plate


15


to be slidable positioned in a horizontal direction. Thus the plate mounter


10


provides for positioning in three different coordinate axis.




Slidable mounted on horizontal slide


11


is a first alignment guide


18




a


, a second alignment guide


18




b


, and a third alignment guide


18




c


which are positionable laterally along horizontal slide


11


for mounting and supporting a printing plate thereon as the printing plate is transferred to a sticky back cylinder.




The alignment guide


18




a


, which is shown in greater detail in FIG.


3


. and

FIG. 3



a


includes a vacuum cup


19




a


having a first end


19




a


′ and a second end


19




a


″. Also included on horizontal slide


11


are two identical alignment guides


18




b


and


18




c


with second alignment guide


18




b


having a vacuum cup


19




b


having a first end


19




b


′ and a second end


19




b


″ and third alignment guide


18




b


having a vacuum cup


19




c


having a first end


19




c


′ and a second end


19




c


″. Each of the alignment guides are slidably positionable along horizontal slide


11


and can be secured in position by a pressure clamp that engages slide


11


. First alignment guide


18




a


is securable by a first clamp


46




a


, second alignment guide


18




b


is securable by a second clamp


46




b


, and third alignment guide


18




c


is securable by a third clamp


46




c


. Each of the alignment guides are independently positionable along horizontal slide


11


to enable an operator to precisely position the alignment guides with respect to a flexographic printing plate.





FIG. 1

shows that each of the vacuum cups


19




a


,


19




b


and


19




c


connect to a vacuum source. A first end


20




a


of flexible vacuum tube


20


connects to vacuum cup


19




b


and a second end


20




b


of flexible vacuum tube


20


connected to a foot operated vacuum source


22


. In addition, a second flexible vacuum tube


21


has one end


21




c


connected to a foot operated vacuum


23


. The other end of vacuum tube


21


bifurcates with one bifurcated end


21




a


connected to end vacuum cup


19




a


and the other bifurcated end


21




b


connected to vacuum cup


19




c


. The e first foot operable vacuum source


22


and second foot operable vacuum source


23


independently control a vacuum suction to allow vacuum cups


19




a


,


19




b


and


19




c


to mechanically align with their alignment tar gets on the printing plate after the targets and the vacuum cups have been visually aligned. The purpose of having a separate vacuum source or separate control of a vacuum source one of the alignment cups is to allow a user to align only one of the vacuum cups with one of the targets and then en gage and hold the printing plate while the other targets are aligned with the other vacuum cups.

FIG. 2

shows a portion of a flexographic printing plate


27


composed of resilient flexible photopolymer which is transparent, allowing for see through visual alignment.




In order to provide precise alignment of the vacuum cups with a reference mark


45


on the sticky back cylinder


30


a laser generator


78


, which is mounted on slide


11


is positioned so that the laser beam projection


78




a


is in alignment with the vacuum cup aligning members. Consequently, by raising and lowering the slide one can position the laser beam


78




a


to be in precise alignment with the mark


45


on the sticky back cylinder


30


and thus have the aligning members in the vacuum cups as well as the reference channels in the flexographic plate


27


in precise alignment for transfer to the sticky back cylinder.





FIG. 2

shows a portion of a flexographic printing plate


27


composed of resilient flexible photopolymer which is transparent, allowing for see through visual alignment. Flexographic printing plate


27


is made from a photo polymer with the printing plate including raised or protruding printing areas


70


and an alignment target


28


, target


28


which also protrudes from flexographic printing plate


27


. Thus target


28


as well as printing areas


70


are integral with flexographic printing plate


27


. Target


28


has an outer annular channel


35


recessed therein. Located concentrically within circular channel


35


is a circular recess


36


. Running diametrically through circular channel


35


is a connecting channel


37


that connects central recess


36


and circular channel


35


. The purpose of connection channel


37


is to allow a vacuum drawn at the central recess


36


to also be drawn at annular channel


35


and radially beyond to bring the end cup


19




a


′ into engagement with the target


28


.




For ease in viewing a vacuum cup


19




a


is positioned next to flexographic printing plate


27


Vacuum cup


19




a


has a first end


19




a


′ and a second end


19




a


″. Protruding from the first end


19




a


′ of vacuum cup


19




a


is a first end


24




a


of outer annular member


24


composed of a rigid material. Annular member


24


comprises an aligning member for aligning the target


28


with the printing plate mounter. Outer annular member


24


has a first end


24




a


having a first opening


32


and a second opening


33


which are shown diametrically opposed to one another to allow for a vacuum to be drawn in the region outside of outer annular member


24


and beneath end


19




a


′ by a vacuum source which is connected to annular member


25


.





FIG. 2

,


3


and


3




a


show that located within first annular member


24


is a second annular member


25


composed of a rigid material. Annular member


25


comprises a second aligning member for aligning target


28


with the printing plate mounter. Second annular member


25


has a first annular end


25




a


. The first annular end


25




a


of second annular member


25


is shown protruding from first end


19




a


′ of vacuum cup


19




a


. Located within second annular member


25


is a vacuum passage


26


for vacuum suction to flow through. Located between the first end


24




a


of first annular member


24


and the first end


25




a


of second annular member


25


is an annular recess


40


.





FIG. 3

is a side view of vacuum cup


19




a


shown in

FIG. 2. A

second end


25




b


of second annular member


25


is shown protruding from the second end


19




a


″ of vacuum cup


19




a


which allows for second flexible tube


21


to connect to vacuum tube


19




a.







FIG. 3



a


shows a cross-sectional view of

FIG. 3

taken along lines


3




a





3




a


. First annular member


24


is shown extending from within vacuum cup


19




a


and protruding out of first end


19




a


′ of vacuum cup


19




a


. Second annular member


25


is shown running through vacuum cup


19




a


and extending from both the first end


19




a


′ of vacuum cup


19




a


and a second end


19




a


″ of vacuum cup


19




a


. Vacuum passage


26


is also shown extending from the first end


19




a


′ of vacuum cup


19




a


to the second end


19




a


″ of vacuum cup


19




a


. The end


24




a


of outer annular member


24


and annual member


25




a


are shown extending outward to a common plane “p” which is recessed from a plane extending through the circumferential edge


19




e


of vacuum cup


19




a.






In order to appreciate the alignment target and how it coacts with a vacuum cup reference should be made to

FIGS. 4

,


4




a


,


5


and


5




a


.

FIG. 4

Shows a top view of alignment target


28


in

FIG. 2

with outer annular channel


35


positioned radially outward of central recess


36


.





FIG. 4



a


show a cross-sectional view of

FIG. 4

taken along lines


4




a





4




a


showing outer annular channel


35


and central recess


36


located therein. Channel


35


and recess


36


have been formed during the etching process when printing areas


70


were also etched in plate


27


. Consequently, the position of target alignment guide can be precisely controlled in relation to the printing areas


70


. As a result the target


28


forms a precise marker for positioning the printing plate


27


. Although the target forms a precise marker for positioning the printing plate it still requires one to precisely pickup and transfer the print plate to a sticky back cylinder.





FIG. 5

is an enlarged view showing side


35




a


and side


35




b


having a generally inward slope that converges toward the bottom


35




c


of annular channel


35


. As shown the converging sidewalls of annular channel


35


and circular recess


36


are obtained by the etching process used to create the recess in target


28


.

FIG. 5

illustrated how the target may be aligned during a visual alignment step.





FIG. 6

shows a cross-sectional view of the placing of printing plate


27


on vacuum cup


19




b


. The present process of mounting printing plate on vacuum cup


19




b


is a two step process. In the first step the target


28


is visually aligned and in the second step a vacuum is applied to the vacuum cup to mechanical align the target and the printing plate as well as to provide support for the printing plate to enable the printing plate to be transferred to a sticky back cylinder. As the printing plate comprises a transparent material the viewer can view the outer annular member


24




a


and inner annular member


25




a


from the underside of the print plate as illustrated by the arrow and schematic positioning of an eye. During the visual aligning step printing plate is slid laterally until the annular member


24




a


is in alignment with outer annular channel


35


and annular member


25




a


is in alignment with central recess


36


. This completes the first step in the alignment process.

FIG. 5

illustrates that during this visual alignment process there may be slight misalignment of annular member


24




a


with annular channel


35


as illustrated by annular member


24




a


engaging side wall


35




b


and not sidewall


35




a


. That is, a vacuum can draw the printing plate alignment target


28


and the alignment member


14


on the vacuum cup from a state of misalignment, if any, into precise mechanical alignment for transfer to a printing cylinder. Thus if during visual alignment step the annual member


24




a


is not fully seated within annular channel


35


the mechanically aligning step achieved through vacuum provides the necessary precise alignment.

FIG. 5



a


illustrates the condition after precise mechanical alignment wherein annular member is fully seated within annular channel


35


and precisely aligned within annular channel


35


.




To appreciate the step of precisely aligning the annular channel


35


with the annular member


24




a


reference should be made to FIG.


6


.

FIG. 6

shows plate


27


with target


28


positioned over annular members


24




a


and


25




a


With the target channels visually aligned with the annular members


24




a


and


25




a


the operator presses on foot vacuum


22


(

FIG. 1

) which produces a vacuum in passage


26


by drawing air through passage


26


. The arrows indicate that air is drawn from region


73


between target


28


and vacuum cup


19




b


and flows through opening


33


and


32


and into annular region


74


where it flow along channel


37


and then outward along vacuum passage


26


. Drawing a vacuum through passage


26


produces a two fold effect. First it provides an axial force that centers or aligns the two annular members


24




a


and


25




a


with the target


28


. This step is illustrated in

FIG. 5



a


which shows that annular member


24




a


has been drawn inward into alignment with annular channel


35


. Thus the drawing of vacuum produces a precise mechanical alignment of the target with the annular members through the coaction of the vacuum forces and the sloping side walls


35




a


and


35




b


which force the annular member


24




a


into a centered position in channel


35


. Second the vacuum provides a holding force to maintain the printing plate in position. That is the vacuum force generated by vacuum cup


19




b


provides a force to hold the printing plate in alignment position to permit handling of the printing plate in the plate mounter


10


.




In the process of the invention, a first vacuum cup is visually aligned and then mechanically aligned by drawing a vacuum with foot vacuum


22


. If more vacuum cups are used as for example vacuum cups


19




a


and


19




c


as shown in

FIG. 1

the vacuum cups are positioned along slide


11


until both vacuum cups


19




a


and


19




c


are in visual alignment. Once in visual alignment the foot operated vacuum is activated to align the vacuum cups


19




a


and


19




c


with their respective targets. Once aligned the clamps can be secured to lock the vacuum cups in position.




With multiple vacuum cups a user can support larger printing plates as well as ensure that the printing plate is properly aligned. The preferred embodiment includes three vacuum cups but the actual number of vacuum cups required can be more or less than three. In general, the number of vacuum cups required is dependent on the size of the printing plates, larger printing plates requiring more vacuum cups while smaller printing plates requiring less vacuum cups.




With the printing plate now firmly held and precisely positioned on mounter


10


through the vacuum cups the final step of transfer of the printing plate to the sticky back cylinder can now be achieved.





FIG. 7

shows a side view of sticky back cylinder


30


and vacuum printing plate mounter


10


in a down position, which is when second arm


13


is parallel with the second mounting bracket


17




b


. In the down position third vacuum cup


19




c


is shown supporting the printing plate


27


, in addition vacuum cups


19




a


and


19




b


(

FIG. 1

) would also provide support of printing plate


27


. In this condition the printing plate


27


is now ready for transfer to the sticky back cylinder


30


.





FIG. 8

shows a side view of printing cylinder


30


and vacuum printing plate mounter


10


moved from a down position to an up position. In the up position the printing plate


27


can be transferred to the sticky back cylinder


30


. In the up position second arm


13


is perpendicular with second mounting bracket


17




b


. Note, sticky back cylinder


30


, has a location mark


45


, which is precisely angularly positioned so as to precisely receive flexographic printing plate


27


. That is, printing plate


27


can be precisely positioned on sticky back cylinder


30


since the location of printing plate


27


with respect to mounter


10


is precisely known. The vacuum cups


19




c


and


19




a


(see

FIG. 1

) and


19




b


(see

FIG. 1

) supports flexographic printing plate


27


during the up position. It is in the up position that vacuum printing plate mounter


10


can transfer flexographic printing plate


27


to a sticky back cylinder


30


at the engaging point


45


of sticky back cylinder


30


.




Once in the up position the printing plate


27


can be positioned vertically by first alignment slide


47




a


and the second alignment slide


47




b


, shown in

FIG. 1

, so as to precisely align flexographic printing plate


27


with the engaging point


45


on sticky back cylinder


30


.




Flexographic printing plate


27


can be transferred to the engaging point


45


of sticky back cylinder


30


by the transverse slides


16




a


and


16




b


which allow the mounter arms


12


and


13


to move toward sticky back cylinder


30


. Once the backside of flexographic printing plate


27


engages sticky back cylinder


30


the vacuum suction to vacuum cup


19




a


,


19




b


and


19




c


is cutoff thus releasing the support that vacuum cup


19




c


has on flexographic printing plate


27


. Next the arms


12


and


13


are moved away from cylinder


30


and the sticky back cylinder is rotated to circumferentially secure the flexible plate in a printing position on cylinder


30


.



Claims
  • 1. An apparatus for mounting a printing plate comprising:a support, said support moveable from a first position to a second position; a vacuum cup having a first end and a second end and a circumferential rim, said vacuum cup connected to said support, said vacuum cup second end having an aligning member, said aligning member comprises an outer annular member, said outer annular member having a passage therein to permit a vacuum to be drawn in a region radially outward of the outer annular member but radially inward of said circumferential rim of the vacuum cup to cause the vacuum cup to engage and support the printing plate thereon; and a vacuum source, said vacuum source connected to said first end of said vacuum cup to permit an operator to control a suction force on said vacuum cup so that when a target on the printing plate is visually aligned with said aligning member the suction force causes the vacuum cup to simultaneously mechanically align the target with the aligning member and to provide a holding support for the printing plate.
  • 2. The apparatus of claim 1 wherein said support includes a slide for positionably supporting said vacuum cup.
  • 3. The apparatus of claim 2 including a mounter having a clamp for securing said vacuum cup in fixed position on said slide.
  • 4. The apparatus of claim 1 including a further aligning member coaxially positioned with respect to said outer annular member.
  • 5. The apparatus of claim 4 wherein both of said aligning members are concentrically positioned within said vacuum cup.
  • 6. An apparatus for mounting printing plates comprising:a horizontal slide, said horizontal slide having a first end and a second end; a first arm moveable from a first position to a second position and having a first end and a second end, said first arm connected to said first end of said horizontal slide; a second arm moveable from the first position to the second position and having a first end and a second end, said second arm connected to said second end of said horizontal slide; a rotatable shaft having a first end and a second end, said first end of said rotatable shaft connected to said second end of said first arm, said second end of said rotatable shaft connected to said second end of said second arm; a first bearing and a first bearing block, said first bearing and said first bearing block encircling said first end of said rotatable shaft; a second bearing and a second bearing block, said second bearing and said second bearing block encircling said second end of said rotatable shaft; a base plate having a first end and a second end, said first end of said base plate connected to said first bearing block, said second end of said base plate connected to said second bearing block; a first horizontal slide and a second horizontal slide, said first horizontal slide attached to said first end of said base plate, said second horizontal slide attached to said second end of said base plate; a first mounting bracket and a second mounting bracket, said first mounting bracket attached to said first horizontal slide, said second mounting bracket attached to said second horizontal slide; a first alignment guide, a second alignment guide, and a third alignment guide, said alignment guides attached to said horizontal slide between said first arm and said second arm; a first vacuum cup, a second vacuum cup, and a third vacuum cup, said vacuum cups composed of a flexible resilient material, said first vacuum cup having a first end and a second end, said second vacuum cup having a first end and a second end, and said third vacuum cup having a first end and a second end, said first vacuum cup connected to said first alignment guide, said second vacuum cup attached to said second alignment guide, and said third vacuum cup attached to said third alignment guide; a first vacuum tube composed of a flexible material, said first vacuum tube having a first end and a second end, said first end of said first vacuum tube connected to said second end of said second vacuum cup; a second vacuum tube composed of a flexible material, said second vacuum tube having a first end, a second end, and a third end; said first end of said second vacuum tube connected to said second end of said first vacuum cup, said second end of said second vacuum tube connected to said second end of said third vacuum cup; and a first foot operable vacuum source and a second foot operable vacuum source, said first foot operable vacuum source connected to said second end of said first vacuum tube, said second foot operable vacuum source connected to said third end of said second vacuum tube, said first foot operable vacuum source and said second foot operable vacuum source control a vacuum suction of said vacuum cups so that when the printing plate is visually aligned with said vacuum cups at targets on said printing plate, in a down position of said arms, said suction is created by said first foot operable vacuum source and said second foot operable vacuum source allowing said vacuum cups to mechanically align with said targets and to support said printing plate, said printing plate adapted to be secured and mounted to a sticky cylinder by moving said arms from said down position to an up position.
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Number Name Date Kind
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Entry
Swing Arm Photopolmer Pin Register System: “Increased accuracy, increased production for photopolyer plate mounting.” no date.
Swing Arm Photopolymer Pin Register System: The post-process punch that keeps photopolymer plate registration “on target.” no date.